


How One Became Three

by LadyPterosaur



Category: Undertale (Video Game)
Genre: Adoption, Babybones, Found Family, Gen, Orphans, Some Fluff, Some adventure, adoptive dadster, just to advance the plot, maybe child abandonment I haven't decided that far, minor OC's - Freeform, pry angst at some point
Language: English
Status: In-Progress
Published: 2015-12-16
Updated: 2016-01-06
Packaged: 2018-05-07 02:02:00
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 3,326
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5439332
Author URL: https://archiveofourown.org/users/LadyPterosaur/pseuds/LadyPterosaur
Summary: <blockquote class="userstuff">
              <p>A small child in a over-sized coat has been seen playing a dangerous game, running about the core construction site as though it was a playground.  Having given the security guards the run around, Gaster has taken it upon himself to catch him...before tragedy happens.</p>
            </blockquote>





	1. Time for a Plan

**Author's Note:**

> {this means signing}
> 
> Might be edited more in the future. Since I'm still not 100% on it, but if I keep editing it's never gonna get done and posted.

"I saw him again today you know." a dull orange slime monster explained to the coworker next to her. "Hoping around the construction site like it was a playground."

"What's the point in hiring security if they can't even keep one kid out..."

Gaster had been listening in on the conversation between some of the interns in the lab, it was mostly gossip but the topic of the little boy had been brought up again. From his understanding for the past few weeks a child monster had been sneaking into the lab and construction site complex. Nobody really knew why but reports state seeing him trying to steal things and rummaging around in the dumpster.

He himself had caught a glimpse while inspecting the current work progress at the site. The young boy in the over-sized blue coat, arms clutching something or other. He'd quickly vanished before the doctor could even get close, disappearing into the clutter of the construction.

Giving an audible sigh the tall skeleton leaned back in his work chair, catching the attention of the two other monsters in the room.

"Something wrong Dr. Gaster?" the orange one, Julie, inquired.

Gaster face was creased with worry and with with a lack of sleep from overworking the past few days. Glancing over at the two assistants and placing the coffee mug he'd been holding on the table, he began signing. {Something really needs to be done about this. What are their parents even doing? It's very irresponsible.}

The two just shrugged in response, Julie speaking up. "Well if anybody ever manages to catch him maybe we'd find out. That boy is playing a dangerous game running around the construction site like that. He is liable to get hurt or worse."

"Yeah. But not even security can get a hold of him. He is pretty fast for a little guy."

This got Gaster thinking, one hand coming up, subconsciously tapping a slender finger against his chin. He'd gone quiet and his face looked contemplative about something, sipping coffee almost on reflex.

The two interns gave each other a resigned glance before turning back the papers in front of them. They knew when the doc had that face on he'd not respond until he was good and ready. Anyway they still had a lot of work to do in working out the complex math for the CORE project, the building might have started but that didn't mean the calculations where complete. The lab once again fell silent.

However this only lasted less then ten minutes before Gaster snapped his fingers, causing the two other monsters to turn around in surprise. {I have a plan.}

"A plan? A plan for what?" the second intern, Aris, a blue dinosaur asked with a curious eyebrow raised.

{Why a plan to catch the child and solve securities problem.} he beamed.

The two just looked at each other and then back to the doctor, waiting for him to continue.

{I propose a stake out. I will hide out and wait for the boy to appear and then I will follow him. See where he goes and if need be...} He didn't finish his thought. Gaster wanted to hope for the best and reluctantly confront the boys parents over their irresponsible childcare. He didn't want to think of the alternate version of events that could lead to a child living dangerously like that. 

"Wait Doc, you? Why not tell security or the royal guards your idea and have them take care of it? You're the royal scientist, it's not really your problem to handle a stray kid."

Aris had a point.

{Nonsense} face giving a half smile. {Since they have been proven ineffectual up to this point, then It is up to me to take on this task. Something needs to be done about his soon before there are consequences.}

"But..." Gaster just gave them a slight glare and the two put up their hands in resignation before turning back to work. "Whatever you say doc."

Satisfied at last the skeleton returned to his own work. He was unsure why he had wanted to do this all on his own but something within him compelled him to do it. It's like he had this gut feeling that he couldn't put his finger on. A need to catch the small boy that eluded so many others.

He'd be the one to finally capture him.


	2. The Chase

**Summary for the Chapter:**

> In which a plan comes together and the mystery deepens

**Notes for the Chapter:**

> I literally just finished this at like 5:30am and it pry has lots of mistakes that I'm gonna have to fix later.

As it turns out trying to catch stray children was much harder then Gaster thought. He'd first tried to stake out the CORE construction site, waiting and watching for his chance. But every time he'd start getting close, every time he thinks that this will finally be the time, he fails. The boy was quick and would disappear into some hiding place or another before the doctor could follow.

This went on for over a week. It was rather frustrating and Gaster's assistants could tell it was really starting to get to him.

"Still no luck huh?" Julie piped up, noticing the visible furrows on the doctors brow.

Gaster gave a tired sigh. {No} he slowly signed, leaning back into his old work chair. {Every time I think I have him he slips away. The construction site is to big and to cluttered.}

"Why not try plan B?" Aris interjected from her workstation across the room. Gaster gave her a curious look in return. "You know that the construction site is not the only place he's seen running around."

It took Gaster a minute but then realization dawned on him. {That's right. He's also seen rummaging around in the labs dumpsters hasn't he.}

"That's right. The janitor mentioned just the other day that he saw him in there again, he looked to be scrounging around for cafeteria leftovers." Shaking her head sadly. "The poor thing."

Gasters face twisted a bit, expression showing quite a bit of concern at such a statement. {Now I really want to know whats going on if the child has to resort to dumpster diving. I do not like the implications this brings up.}

The three fell silent. The interns could only look at each other, their faces now sharing the same concern that Gasters did.

{Hopefully tonight proves to be a success.} The doctors face now filled with determination as he turned back to his work. Tonight would be the night. It had to be.

\------

As 'night' in the underground fell and the rest of lab had gone home for the evening, Gaster was instead making his way towards the back of the building. He was primed and ready for the stake out, having found a good hiding spot behind a stack of old cardboard boxes.

Squeezing his tall frame down as low as he could, positioning himself in such a way that he could clearly see the dumpsters but he himself would remain in relative shadow. It did help that he normally wore such dark clothing, though the white of his bones was a bit harder to conceal. He'd hope the boy wouldn't notice.

And so he sat and waited and waited and waited some more. Hours passed with no sign of the boy. Gaster gave a soft sigh and wondered if the night was gonna be a total bust, after all reports said that the child didn't came to the dumpsters every day.

He was about to pack it in and call it a night when a flash of something caught the doctors attention. Gaster froze, eyes fixated on the dumpsters. Until he saw what he'd been waiting for, the small child in the over-sized blue coat.

Gaster watched as the little monster cautiously approached, going to great pains to try and remain unseen. Looking around nervously to make sure nobody else was around. The boy then slowly and carefully pulled himself up and into the trash, attempting to make as little noise as possible. Though he was failing miserably as even from that distance Gaster could hear the sounds of plastic and the clattering of cans.

He'd not stayed there long. Just like that the kid awkwardly climbed out, arms clutching scraps and pockets stuffed with whatever supplies he could get hold of. Then he was off again.

Gaster wasn't about to let the young monster get away this time. He was determined.

With haste the doctor started after the child, keeping a safe distance away. He made sure to keep to the shadows as much as possible, quickly taking any cover that presented itself in his goal to remain unseen.

It was rough going. The boy would constantly start and stop and look around, like he knew something was off. Like he knew somebody was watching. But Gaster never faltered in his goal of tailing the kid.

They had gone quiet the back way through Hotland, twisting and turning through back alleys and small narrow passageways the doted the sparse residential area. But in the end it looked like the child never spotted him, as their pace slowed to a more steady walk. They must have been in an area of safety to the child.

Gasters hard work and patience pays off.

The young one finally stopped in front of an old crumbling house on the outskirts of Hotland. Giving one final glance around to make sure the coast was clear, he disappeared inside.

Carefully Gaster made his way over to the old building, trying his best to make his footfalls as quiet as possible. After all this hard work the last thing he wanted was to alert the boy to his presence.

Siding up to a window, the doctor decided to risk a glance inside. Only to be greeted with dust and darkness and no visible sign of the young monster in the blue hoodie. But despite having no visual, there was definitely some sort of noise coming from within the building. It sounded like...talking.

Yes it was indeed talking, as a young voice drifted from the back room that was out of sight of the older monster. It must have been the boy in the hoodie. But who was he talking to? Gaster thought it must be a parent of some sort but the audio of the second voice didn't seem to really hold any meaning at all.

Maybe an animal of some kind?

Gaster needed to try and get closer. Try to make out what the voice was saying, figure its meaning and hope that it held clues to the boy and his situation. He tried to find a foothold, tried to find a way to maybe lean in closer, to strain his hearing to listen in to the conversation at hand. Only for his foot to slip on the smooth stone.

Flailing about Gaster grasped at the windows edge to balance himself, inadvertently causing a few loose stones to tumble to the earth below. They clattered against the ground, seeming much louder then they really were. Cursing at his clumsiness as he heard the voices from inside stop suddenly. They had heard him.

Everything went still. The doctor didn't move and neither did any of the occupants inside the house. But then...footsteps. Loud and hurried coming around from the back of the building. And there he was, the young monster that Gaster had been trying his hardest for the past week to get a hold of, looking him straight in the face from the side of the house.

The child's eyes betrayed his fear as he looked at the tall form of older monster before him. It was no secret that the royal scientist could look rather imposing, what with him being unnaturally tall and thin. The cracks along his face, remnants from a rather explosive accident, really didn't help him look any friendlier.

For a brief moment nobody moved. Gaster looked at the kid and the kid looked right back at Gaster. Eye sockets locked on each other.

The boy was the first to move. Dashing off away from the house, arms flailing in every direction in an effort to keep the doctors attention. "so you managed to find my secret hiding place." He called out in what Gaster could only assume was suppose to be an imposing tone, it wasn't. "well...well you can't catch me."

The young monster motioned as though he fully intended to run off and allow the chase to begin, but was stopped in his tracks when he took notice that Gaster was making no moves to give chase. "come on." he egged.

The rouse was plain to see, Gaster could tell the child obviously didn't want him to find whatever was inside the crumbling building. So instead of giving chase and potentially losing the child among the back alleys and streets, he instead turned around.

"wait..."

Gaster didn't.

"please...st..."

Gaster reached out to push open the old door.

"STOP"

Gaster froze. His soul griped by some invisible force and before he could even realize what was happening, he slammed down hard.

**Notes for the Chapter:**

> Sorry for the stupid long wait on this. Life and writers block are my eternal tormentors.


	3. The Fall

**Summary for the Chapter:**

> In which Gaster is finally on track but not everything goes to plan.

The boy had run away terrified, eyes betraying fear at the repercussions of his actions. He had let his emotions get the better of him, magic flaring up and he'd lashed out with all he had.

Now attacking an adult was bad enough, but to attack the royal scientist of all monsters? They'd take him away, they'd lock him up in some bad place to never be seen again. Just the thought of it scared him down to his core and so he ran. 

He ran as fast as his tiny legs could take him, not even daring a glance back towards the house. Knowing full well who he'd left and hoping against hope they'd be okay. He'd come back... he'd hope he could come back. As long as he got away, as long as he could hide and not get caught, he'd come back.

Where exactly he was going the boy wasn't quite sure, his legs were on autopilot at this point. Traversing familiar ground through Hotlands barren streets and walkways.  
An idea formed and he found himself turning towards familiar ground. To a place that he knew well enough that he could hide and hope that the scientist he'd left sprawled upon the ground would not find him.

\--------

Back at the house Gaster was left just laying there a bit aghast, his head still ringing a bit from smacking against the rocky earth. The child certainly had some strong magic about him that was for sure and it had caught the scientist completely off-guard to say the least. 

Slowly and shakily he got himself back on his feet, dusting off his coat in the process. He then started checking his various limbs and bones for any sort of injury from his encounter with the ground. Nothing broken, Gaster thought to himself in relief, after all he wasn't really the sturdiest of monsters. 

But a realization was now dawning on his face. The boy! He looked around in a mild panic, only to be greeted with a deserted alleyway. Gaster cursed at himself for losing the boy again before a thought occurred to him. The child had used his magic. He'd be able to use his own magic to sense the young monster, it wasn't to late he'd still be able to catch him.

Using his own magic Gaster scanned the area around him. Though he could still sense the young monsters magical energy, it was weak and getting farther away. It was also heading in the direction of the CORE construction site.

Oh no. Oh no no no no no this is not good. Gaster paced about nervously before taking off in the same direction he felt the young monster was heading. He really hoped he could catch up to him quickly or better yet he was sensing wrong and the child had headed off to a much safer location.

The road back to the lab was a relatively quick affair. There was no physical sign of the boy anywhere around and a quick inquiry from passing lab janitorial staff yielded no clues. Though it did raise some questions on what the royal scientist was doing running around in a state of nervous panic that time of night.

"Say Doc whats got you in such a rush tonight? Shouldn't you be home by now?"

{Nothing really. Just passing through} he'd quickly signed.

The other monster just gave Gaster a weird look before waving it off. The scientist was well known for being a bit on the eccentric side as is. "Whatever you say doc."

Hurriedly he'd waved the staff off before any more questions could be asked, heading in the direction of the construction site. Gaster didn't want to worry them or get anyone else involved if he didn't have to. Feeling if more adults all came looking for the kid, it could cause more harm then good. After all, a scared child with unusually high magical ability being surrounded could lead to tragedy. 

No he'd have to take care of this himself...somehow.

The CORE construction area was how he'd expected it, devoid of life, the workers having gone home for the night. With only the natural sounds of Hotland punctuating the quite air or so it seemed at first. There was another sound, very faint but it was still there. The sound of crying.

Carefully Gaster followed the noise, not wanting to rush the boy and cause him anymore undue alarm. But even with the sounds and a general direction, it was hard to really pinpoint where the young monster could be hiding. After all the site was littered with work materials and piles of debris, innumerable crevasses for such a small monster to hide.  
He hesitated. Taking a deep breath before resigning himself to do what he didn't like.

"Hello..." he calmly called out in his strange raspy voice. Gaster rarely spoke, signing being a much more comfortable method for him. After all his voice was known to be a bit hard to understand even at the best of times. But he wouldn't be able to get the child's attention by signing, so it was worth a shot.

The crying stopped, at least for the moment, but the young one seemed unable to hold it back. Sniffling as he answered. "go away."

"Please don't be frightened." Gaster picked his words carefully "I'm not going to hurt you."

"but...but.." the crying was coming back in full force.

"It's okay. You can come out" He tried to reassure the boy. "It's okay."

"but..." the child's voice was shaky as he hesitantly began to back out of his hiding place. 

Gaster could see him emerge slowly from behind a stack of metal pipes, his face flushed from crying. He didn't stop though, he kept backing up, trying his best to put some distance between him and the doctor. 

"...i didn't mean to. please... i didn't..." he stammered out, hands rubbing against each other nervously. He continued stepping backwards and was getting dangerously close to the edge.

"It's okay." Gaster knelt down, bringing himself more at eye level with the child. Trying to make himself seem less of a threat. "Please just stay still. Everything will be okay... just come here..." The doctors eyes betraying a nervousness that was creeping into his voice as well.

"but...but i'm gonna get in trouble. their going to send me away... i... do..." he was cut off as one foot caught the edge of his over sized jacket. He could feel himself falling backwards into empty air as ground gave way beneath his feet. 

He began to fall.

Time felt like it was moving in slow motion. Gaster could see the child falling and his own body rushing forward, trying to grasp the boy. But he found his hands grasping only air as the child slipped from his reach, face painted with surprised shock and horror. 

**Notes for the Chapter:**

> you can find a full size image on my tumblr:  
> http://gravityfallspterosaur.tumblr.com/post/134587591881/sketch-that-got-a-little-out-of-hand-its-a-scene  
> which you can also find more of my art on that tumblr (it is strictly an art blog). That post also has the original draft for chapter 3 before major editing happened X3

**Author's Note:**

> This is like my first fanfic ever. So hopefully it isn't to to bad.


End file.
